This section specifies criteria that your test system must meet for updating and recording data. It also specifies criteria for controlling the systems related to driver demand, the dynamometer, sampling equipment, and measurement instruments.
(a) Read and record values and calculate mean values relative to a specified frequency as follows:
(1) This paragraph (a)(1) applies where we specify a minimum command and control frequency that is greater than the minimum recording frequency, such as for sample flow rates from a CVS that does not have a heat exchanger. For these measurements, the rate at which you read and interpret the signal must be at least as frequent as the minimum command and control frequency. You may record values at the same frequency, or you may record them as mean values, as long as the frequency of the mean values meets the minimum recording frequency. You must use all read values, either by recording them or using them to calculate mean values. For example, if your system reads and controls the sample flow rate at 10 Hz, you may record these values at 10 Hz, record them at 5 Hz by averaging pairs of consecutive points together, or record them at 1 Hz by averaging ten consecutive points together.
(2) For all other measured values covered by this section, you may record the values instantaneously or as mean values, consistent with good engineering judgment.
(3) You may not use rolling averages of measured values where a given measured value is included in more than one recorded mean value.
(b) Use data acquisition and control systems that can command, control, and record at the following minimum frequencies:
Table 1 of §1066.125—Data Recording and Control Minimum Frequencies
| Applicable section | Measured values | Minimum command and control frequencya | Minimum recording frequencyb c |
|---|---|---|---|
| §1066.310 §1066.315 |
Vehicle speed | 10 Hz. | |
| §1066.425 | Continuous concentrations of raw or dilute analyzers | 1 Hz. | |
| §1066.425 §1066.501 |
Power analyzer | 1 Hz. | |
| §1066.425 | Bag concentrations of raw or dilute analyzers | 1 mean value per test interval. | |
| 40 CFR 1065.545 §1066.425 |
Diluted exhaust flow rate from a CVS with a heat exchanger upstream of the flow measurement | 1 Hz. | |
| 40 CFR 1065.545 §1066.425 |
Diluted exhaust flow rate from a CVS without a heat exchanger upstream of the flow measurement | 5 Hz | 1 Hz means. |
| 40 CFR 1065.545 §1066.425 |
Dilution air flow if actively controlled (for example, a partial-flow PM sampling system)d | 5 Hz | 1 Hz means. |
| 40 CFR 1065.545 §1066.425 |
Sample flow from a CVS that has a heat exchanger | 1 Hz | 1 Hz. |
| 40 CFR 1065.545 §1066.425 |
Sample flow from a CVS that does not have a heat exchanger | 5 Hz | 1 Hz means. |
| §1066.420 | Ambient temperature | 1 Hz.e | |
| §1066.420 | Ambient humidity | 1 Hz.e | |
| §1066.420 | Heated sample system temperatures, including PM filter face | 1 Hz. |
aCFVs that are not using active control are exempt from meeting this requirement due to their operating principle.
b1 Hz means are data reported from the instrument at a higher frequency, but recorded as a series of 1 s mean values at a rate of 1 Hz.
cFor CFVs in a CVS, the minimum recording frequency is 1 Hz. For CFVs used to control sampling from a CFV CVS, the minimum recording frequency is not applicable.
dThis is not applicable to CVS dilution air.
eUnless specified elsewhere in this part or the standard-setting part. Note that this provision does not apply to soak periods where recording frequencies are not specified. For these instances, we recommend a recording frequency of ≥0.016 Hz.
[79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9120, Feb. 19, 2015]
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